Embodiments of the inventive concept relate generally to semiconductor memory technology. More particularly, embodiments of the inventive concept relate to nonvolatile memory devices and systems capable of performing repair operations for defective memory cells.
Semiconductor memory devices can be roughly divided into two categories according to whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power.
Examples of volatile memory devices include static random-access memory (SRAM) devices, dynamic random-access memory (DRAM) devices, and synchronous dynamic random-access memory (SDRAM) devices. Examples of nonvolatile memory devices include read-only memory (ROM) devices, programmable read-only memory (PROM) devices, electrically programmable read-only memory (EPROM) devices, electrically erasable and programmable read-only memory (EEPROM) devices, flash memory devices, phase-change random-access memory (PRAM) devices, magnetic random-access memory (MRAM) devices, resistive random-access memory (RRAM) devices, and ferroelectric random-access memory (FRAM) devices. Flash memory devices can be further divided into two categories including NOR-type flash memory devices and NAND-type flash memory devices.
Over the past several years, researchers have developed numerous techniques for improving the size, capacity, and performance of various types of memory devices. One of these techniques is to form memory devices with memory cells arranged in a three-dimensional array structure. Such an array structure can potentially improve the amount of data that can be stored within a limited chip area.